Do you have to have your other carrier sim in before you install Blacksn0w?

I am wondering if that is the issue. It is a Fido iPhone 3G - 3.1.2 - 05.11.07 and we had Blacksn0w installed and using a Rogers sim and it was working. We put in a Telus sim and just get no service, Telus doesn't even show up under Carrier.

It is in a Telus 3G area, we even tried d/l and updating a Telus ipcc file and rebooted.